OBD Guide
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B1231

Open In The Evaporator Temperature Sensor Circuit

B1231 is an OBD-II diagnostic trouble code meaning: Open In The Evaporator Temperature Sensor Circuit. Common causes: broken wires to the evaporator temperature sensor, evaporator temperature sensor malfunction. Estimated repair cost: $33–89.

Severity
⚠️ Medium
Can you drive?
Limited driving only, diagnose soon
Approx. repair cost
$33–89 (est.)

Symptoms

  • Insufficient interior cooling
  • The air conditioner is unstable
  • Evaporator freezing
  • Hot air from deflectors

Causes

  • Broken wires to the evaporator temperature sensor
  • Evaporator temperature sensor malfunction
  • Poor contact in the sensor connector
  • Wiring harness damage
  • Malfunction of the climate control control unit

How to Fix

  1. Check the integrity of the wiring harness to the sensor
  2. Check the resistance of the evaporator temperature sensor
  3. Clean the contacts of the sensor connector
  4. Replace evaporator temperature sensor if necessary
  5. Check the operation of the system after repair

Related codes

B1232B1233B1234

FAQ

What does the B1231 code mean?

B1231 is an OBD-II diagnostic trouble code that indicates: Open In The Evaporator Temperature Sensor Circuit

What causes a B1231 error code?

The most common causes of B1231 include: Broken wires to the evaporator temperature sensor; Evaporator temperature sensor malfunction; Poor contact in the sensor connector; Wiring harness damage.

How do I fix a B1231 diagnostic trouble code?

To fix B1231: Check the integrity of the wiring harness to the sensor. Check the resistance of the evaporator temperature sensor. Clean the contacts of the sensor connector. For a complete diagnosis, use an OBD-II scanner.

Is it safe to drive with B1231?

Limited driving only, diagnose soon

How much does it cost to fix B1231?

The estimated repair cost for B1231 is $33–89. Actual cost depends on your vehicle, location, and labor rates.

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See also: Russian version · NationStat